yes the AQUA nighttime band31 https://go.nasa.gov/2u8atAA is pretty definite. Lighter colour shows warmer (than ice surface) seawater in the crack which given the low resolution of the thermal IR band is fairly wide (or does the low resolution make it appear wider?)

There was some keen interest a while back when the crack, which spread across the shelf from a pinning point known as the Gipps Ice Rise, looked as though it might sweep around behind another such anchor called the Bawden Ice Rise. Had that happened, it could have prompted a significant speed-up in the shelf's seaward movement once the berg came off.

As it is, scientists are not now expecting a big change in the speed of the ice.

A giant iceberg twice the size of Luxembourg has broken off an ice shelf on the Antarctic peninsula and is now adrift in the Weddell Sea.

Reported to be “hanging by a thread” last month, the trillion-tonne iceberg was found to have split off from the Larsen C segment of the Larsen ice shelf on Wednesday morning after scientists examined the latest satellite data from the area.

The Larsen C ice shelf is more than 12% smaller in area than before the iceberg broke off – or “calved” – an event that researchers say has changed the landscape of the Antarctic peninsula and left the Larsen C ice shelf at its lowest extent ever recorded.

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"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

The referenced post was from March 2015, so 5 +/- 3 years would be from March 2017 to March 2023, so at least the calving was within my margin of error

This officially leaves the shelf in a concave formation. With the re-arrival of the +PDO/+ENSO favored phase and the encroachment of the -9C annual isotherm on the shelf, the time of stability for Larsen C may be running out.

The referenced post was from March 2015, so 5 +/- 3 years would be from March 2017 to March 2023, so at least the calving was within my margin of error

This officially leaves the shelf in a concave formation. With the re-arrival of the +PDO/+ENSO favored phase and the encroachment of the -9C annual isotherm on the shelf, the time of stability for Larsen C may be running out.

Maybe the rest of the ice shelf will collapse before my March 2023 timeframe ends.

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“It is not the strongest or the most intelligent who will survive but those who can best manage change.” ― Leon C. Megginson

Greetings ASIF, long time lurker here, moved to post by the Larsen C event!

It is fascinating to read the media reaction: many glaciologists seem to be falling over themselves to say there is no reason to think there is any connect to climate change here. I find that weird. Anyway, what I wanted to ask about is this. Dr Adrian Luckman has several times cited a 2015 Scripps study (e.g., in today's Guardian and in theconversation.com) as measuring thickening of Larsen C. As I read the study, it says Larsen C is thinning:

"Volume loss from Antarctic ice shelves is accelerating", Paolo et al Science, 2015: "On the eastern side of the Antarctic Peninsula... the regional ice-shelf thinning rate of 3.8 ± 1.1 m/decade is about half of that on the western side. The onset of thinning for Larsen C has progressed southward, which is consistent with climate-driven forcing discussed in earlier studies. The highest thinning rates on Larsen C (with local maximum thinning of 16.6 ± 8.1 m/decade) are near Bawden Ice Rise."

Proposing the name 'Reagan Iceberg' for the piece of ice shelf that irreversibly separated from the glaciers of West Antarctica. This would be because of the slow pace of heat accumulation in the ocean, the 'thermal inertia' which is too technical an expression for many. This just means that the water takes a while to warm up and the heat that was applied in 1980s would have done the same, though a bit later, possibly in 2030s. Thus we could expect the "Iceberg Tillerson of Drumpfistan" to be launched by the chinese conspirators in 2040s. This would be way larger since the ego size and stupidity difference.

The referenced post was from March 2015, so 5 +/- 3 years would be from March 2017 to March 2023, so at least the calving was within my margin of error

Jeez. I was hoping the scary stuff from Antarctica and Greenland would’ve been decades out. Like 5+ feet after 2040 maybe.

Are you surprised by this break? What’s the next “big” event In Antarctica?

This officially leaves the shelf in a concave formation. With the re-arrival of the +PDO/+ENSO favored phase and the encroachment of the -9C annual isotherm on the shelf, the time of stability for Larsen C may be running out.

Maybe the rest of the ice shelf will collapse before my March 2023 timeframe ends.

Thinking out loud... (sorry!) While a naive view of the impact of this calving would be to see the remainder of the ice shelf do a prompt shuffle to the east, relieving buttressing on land-based ice, I guess the major effect will be increased exposure of the remainder of the ice shelf to open-ocean tidal and thermal dynamics.

It will be interesting to watch for signs of the prompt disintegration of the remainder (which seems unlikely at this stage) and instead I guess we will just continue to see the edge chewed away.

Is there any feature of the ocean floor shape which would alter current dynamics now the calving is done?

It will be interesting to watch the berg's movement from here - it will give us an idea of the net outcome of currents etc acting on it.

RobertM: on the march for science Facebook post, Robert Grumbine mentioned the in-retrospect obvious point that the temperature at the base is barely freezing, while at the surface it's very cold. So there's a temperature gradient through the ice shelf.

Higher temperature at the surface, even a warming from -35 to -30, means a larger region inside the slab of ice that's "warm" and therefore "soft" (in relative term of course), which means it can move faster.

magnamentis

better to amend the name as it was done with the US election thread so that the content remains accessible within the same thread and the discussion will continue seamlessly, this is my proposal, others will make the choice.

A June 6, 2017 PolarView image seems to show less detail, but looking at the ice shelf coast in the area where the rift is likely to go (or went), I think I see (yes: speculation) a lineation at the coast (middle arrow in 'whiter ice' June 6 image) that is not pared with a lineation on the June 4 image ([see June 8 post]). (The other two pairs of arrows identify duplicated lineations.) ...

The actual rift (July 12 PolarView) reached the edge approximately where my 'middle' arrow identified a new lineation. Cool! (Chance?) (images are approximately the same area)

I am aware of that but the figures given by many sites for sea ice go to the last decimal points. There are a lot more ice shelves to go and for the Weddel and Ross Seas the overall percentage is very high. For the same argument we could just omit CAA and the Black Sea / Caspian Sea / Baltic Sea NH sea ice figure but to my understanding, these are calculated to overall winter tally.

. . . but VeliAlbertKallio the satellites have difficulty even with meltponds!! (& clouds, & coastlines, & 15% cut-offs, etc.).I'm sure we can live with the limitations. It is only 12% of the 4th largest iceshelf on the earth . . . there's bigger nits to pick?

It would be kind of fun if the sea ice charts would show 'very old ice' with an estimate of years to develop to such a berg. I guess in this case there should be a number of over at least 8200. Probably much more.

A screen shot from the middle of the rift (July 12 PolarView) very nicely shows the relative movement of the iceberg and the ice shelf: a classic transverse fault. All arrows are parallel and the three sets of collinear arrows have the same spacing between their butt ends. (Is there some deformation in the iceberg or is my arrows' angle slightly off?)

Here is 'just the rift end' at 106%. From the June 8 post's scale, the rift at its end is about 1/2 km wide. Now looking forward to all the 'little' icebergs that we were 'promised'!

Cool image.The chunk of ice in the middle shows it came from above so there must be a surface flow heading south.Some slushy ice entering the crack as well further indicates that.The little map posted above has the currents heading north however.Guess not at the surface...

The dark blue circles are the amphidromic points, around which the tides turn clockwise. I believe they drive the currents, that is the currents are residual persistent flows driven by tidal movements. Image from http://www.esr.org/ptm_index.html

There appears to be some fast ice growing in the young rift between Larsen C and Iceberg A68 (and friends). PolarView screen print. Project MIDAS offers this (screen shot of part of their post's graphic with scale moved and Iceberg label recreated):

Quote

... a new rift appears to be extending northwards (towards the top left) and may result in further ice shelf area loss. Although this new rift will probably soon turn towards the shelf edge, there may be a risk that it will continue on to Bawden Ice Rise, a crucial point of stabilisation for Larsen C Ice Shelf.

magnamentis

is "fast ice" the correct term for ice growing between an iceberg and an ice-shelf?

the question is mean seriously not that you think there would be sarcasm or something i just don't know and like to learn about terms as much as i can, this term just did never cross my mind in this context, hence your feedback will be very appreciated.

ice that is anchored to the shore or ocean bottom, typically over shallow ocean shelves at continental margins; fast ice is defined by the fact that it does not move with the winds or currents.

The new ice attached to (and growing off of) the Larsen C ice shelf is fast ice. The new ice that is attached to the iceberg (ice island) is not fast ice, as long as the iceberg is drifting around. If the iceberg stops moving for a bit, there will temporarily (at least) fast ice between the two. I rather expect the iceberg to get stuck in the winter fast ice later this SH winter. (But I'm not an iceberg expert.)

Iceberg A68 is wrecking havoc on the frozen sea ice off of Larsen C Ice Shelf: at least for now. The crack through the fast ice shown here (PolarView 11 pm on July 18) isn't apparent on the 8 am image (posted above). It is interesting to see how much the little icebergs have moved in 15 hours. The largest of the small icebergs is about 5 x 12 km in size.